Synthesis of 1-phenyi-1H-tetrazolo[4,5-d]tetrazole and 5-aryl-1-(4-bromophenyl)-1,2,4-triazolo[4,3-d]tetrazoles

l-Phenyl-lH-tetrazol-5-yIhydrazine (2) was reacted with nitrous acid to yield 1-phenyl-lH-tetrazolo[4,5-d]tetrazole (3). l-Arylidene-2-(l-phenyl-lH-tetrazol-5-yl)hydrazines (4) were generally reactive towards electrophilic reagents. When treated with bromine in acetic acid, 4 yielded mixtures of 1-arylidene-2-[1-(4-bromophenyl)-lH-tetrazol-5-yl]hydrazines (5a-d) and 2-[1-(4-bromophenyl)-lH-tetrazol-5-yl]hydrazidic bromides (6a-d). Solvolysis of 6a-d in aqueous acetone yielded 5-aryl-1-(4-bromophenyl)-1,2,4-triazolo[4,3-d]tetrazoles (7a-d). The structures of the synthesized compounds were confirmed on the basis of elemental analysis, IR and ¹H NMR data.     

Synthesis of 2-mercaptothieno[3,2-d]- and 2-mercaptobenzo[4, 5]thieno[2,3-d]thiazoles

2-Mercaptothieno[3,2-d]- and 2-mercaptobenzo[4, 5]thieno[2,3-d]thiazoles were synthesized by reduction of bis(3,3′-nitro-2,2′-thienyl) and bis(2,2′-nitrobenzo[b]thien-3,3′-yl) disulfides, respectively, with sodium hydrosulfite or sodium sulfide in the presence of carbon disulfide.     

Synthesis of 2-methylphenanthro[2, 1-d]thiazole

2-Methylphenanthro[2, 1-d]thiazole has been synthesized by the oxidative cyclization of 2-thioacetylaminophenanthrene.     

Selenium heterocycles. XXXII . Synthesis of [1]benzoxepino[3,4-d]-thiazole, [1]benzothiepino[3,4-d]thiazole, [1]benzoxepino[3,4-d]selenazole,and [1]benzothiepino[3,4-d]selenazole. four novel heterocycles

Starting from the readily available ethyl 2-phenyl-4-methyl-thiazole-5-carboxylate (III), 2-phenyl-4-chloromethyl-thiazole (VIII) and 2-aryl-4-chloromethylselenazole (XIV), 2-phenyl-4,10-dihydro-10-oxo-[1]benzoxepino[3,4-d]thiazole (Ia), 2-phenyl-4,10-dihydro-10-oxo[1]benzothiepino[3,4-d]thiazole (Ib), 2-aryl-4,10-dihydro-10-oxo[1]benzoxepino[3,4-d]selenazoles (IIa-IIe) and 2-aryl-4,10-dihydro-10-oxo[1]benzothiepino[3,4-d]selenazoles (IIf-IIj) were prepared.     

Synthesis and characterization of a new pillar[5]arene-based [1]rotaxane

In this study, we reported the synthesis of three kinds of mono-functional pillar[5]arene derivatives PRI, PRII and R and their structures were studied by 1D and 2D NMR spectra and mass spectra. The 2D NMR spectra including ¹H-¹³C HSQC, ¹H-¹H COSY and NOESY spectra indicated that PRI and PRII are both stable self-included pseudo[1]rotaxanes in CDCl₃. These original structures are promising compounds for the design of pillar[5]-based [1]rotaxane. And the results showed that R could exist stable in CDCl₃ and DMSO because of the coordination of N-H?O hydrogen bonding interaction and C-H?π interaction.     

Chemistry of 1,2,3-thiadiazole. IV. Synthesis of [1]benzoxepino-[3,4-d][1,2,3]thiadiazole, [1]benzothiepino-[3,4-d][1,2,3]thiadiazole, [1]benzoxepino[4,3-d][1,2,3]thiadiazole, [1]benzoxepino[4,3-d]oxazole and [1]benzoxepino[4,3-d]oxazole. Four novel heterocycles

Starting from the readily available 4-bromomethy-5-carbethoxy 1,2,3-thiadiazole (V), 5-bromomethy-4-carbethoxy-1,2,3-thiadiazole (IX) and ethyl 2-aryl-5-bromomethyloxazole-4-carboxylate (XIV), 4,10-dihydro-10-oxo[1]benzoxepino[3,4-d][1,2,3]thiadiazole (Ia), 4,10-dihydro-10-oxo[1]benzothiepino[3,4-d][1,2,3]thiadiazole (Ib), 4,10-dihydro-4-oxo[1]benzothiepino[4,3-d] [1,2,3]thiazole (II), 2-aryl-4,10-dihydro-4-oxo[1]benzoxepino[4,3-d]oxazoles (XIXa-XIXc) and 2-aryl-4,10-dihydro-4-oxo[1]benzothiepino[4,3-d]oxazoles (XIXd-XIXf) were prepared.     

Synthesis and anticonvulsant activity of 3H-imidazo[4,5-c]-pyridazine, 1H-imidazo[4,5-d]pyridazine and 1H-benzimidazole analogues of 9-(2-fluorobenzyl)-6-methylamino-9H-purine

The 3H-imidazo[4,5-c]pyridazine, 1H-imidazo[4,5-d]pyridazine, and 1H-benzimidazole analogues of the potent anticonvulsant purine 9-(2-fluorobenzyl)-6-methylamino-9H-purine (1, 78U79) were synthesized and tested for anticonvulsant activity. The 3H-imidazo[4,5-c]pyridazines 8 and 9 were prepared in five stages from 3,4,5-trichloropyridazine (2) . The 1H-imidazolo[4,5-d]pyridazine 15 was synthesized in four stages from 5-[(benzyloxy)methyl]-1,5-dihydro-4H-imidazo[4,5-d] pyridazin-4-one (10a) . The benz-imidazole analogues 18 and 20 were prepared from 2,6-dinitroaniline in three stages. These compounds were one-tenth or less as active as 1 in protecting rats against maximal electroshock-induced seizures.     

Synthesis of [1-15N,2-13C]-labeled difloxacin

Abstract  

The synthesis of [1-¹⁵N,2-¹³C]-difloxacin, an arylfluoroquinolone antibacterial agent, is reported. As a crucial initial step, the starting materials ethyl 2,4,5-trifluorobenzoylacetate, [formyl-¹³C]-triethyl orthoformate, and [¹⁵N]-4-fluoroaniline were reacted to ethyl [¹⁵N,3-¹³C]-3-(4-fluoroanilino)-2-(2,4,5-trifluorobenzoyl)acrylate. After cyclization and ester cleavage, the resulting intermediate was reacted with 1-methylpiperazine to [1-¹⁵N,2-¹³C]-1-(4-fluorophenyl)-6-fluoro-7-(4-methyl-1-piperazinyl)-1,4-dihydro-4-oxoquinoline-3-carboxylate, i.e., [1-¹⁵N,2-¹³C]-difloxacin. The overall yield was 62% based on the non-labeled and 43% based on the labeled starting materials (both used in 1.4 molar excess). The product was identified by ¹H-, ¹³C-, and ¹⁵N-NMR spectroscopy and by cochromatography (TLC, HPLC) with an authentic reference; its purity (HPLC) was above 98%. Prior to synthesis of [1-¹⁵N,2-¹³C]-difloxacin, non-labeled difloxacin was synthesized in order to optimize procedures and to identify and characterize all intermediates.     

1H, 13C and 15N NMR spectra of [1,2-15N2]pyrazole derivatives

The chemical shifts and coupling constants of [1,2-¹⁵N₂]pyrazole, 2-(1-[1,2- ¹⁵N₂]pyrazolyl)-2-[l,3-²H₆]propanol, 1-nitro[1,2¹⁵N₂] and 3-nitro[1,2-¹⁵N₂]pyrazole are reported.     

Synthesis and complete 1H, 13C and 15N NMR assignment of substituted isoxazolo[3,4-d]pyridazin-7(6H)-ones

The synthesis and complete assignment of all hydrogen, carbon and nitrogen NMR signals of several new isoxazolo[3,4-d]pyridazin-7(6H)-ones is reported. The spectroscopic characterization is extended to previously described analogues.     

Synthesis and 13C, 15N NMR study of a new functionalized pyrido[2,3-b]indole derivative

New functionalized α-carbolinones especially the 4-hydroxy-3-nitro-1H,9H-pyrido[2,3-b]indol-2-one were synthesized in a good yield, three-step reaction. A complete ¹³C, ¹⁵N nmr study of this carbolinone and precursors is presented.     

Synthesis of 2-methyl-5-phenylthieno[2,3-d]thiazole

The synthesis of a new heterocyclic base — 2-methyl-5-phenylthieno[2,3-d]thiazole — is described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, 1624–1625, December, 1970.     

Synthesis and 13C-NMR study of novel pyrazolo[5′,1′:3, 4][1, 2, 4]triazino[5, 6-d]pyrimidines

The pyrazolo[5′, 1′:3, 4][1, 2, 4]triazino[5, 6-d]pyrimidines 5a-c, 6 were synthesized from the pyrazolo[5, 1-c]-[1, 2, 4]triazines 1a, c and the ring carbon signals of 5a-c, 6 were assigned by the aid of coupling constant [J( 13 C-¹H)] data.     

Synthesis of 1H-imidazo[3′,4′:4,5]thieno[2,3-b]pyridines. A new ring system

A facile and convenient synthesis of the title compounds is described, using as starting materials the 2-nitro-3-aminothieno[2,3-b]pyridines. Mass spectral data of the above mentioned compounds are briefly discussed.     

Synthesis of 2-phenylthieno[3,2-d]oxazole and 2-phenylthieno[3,2-d]thiazole

2-Phenylthieno[3,2-d]oxazole and 2-phenylthieno[3,2-d]thiazole were obtained by cyclization of the corresponding 2-phenyloxazole and 2-phenylthiazole derivatives. Their spectra and chemical properties were studied, and the pK_a values of carboxylic acids with other two-ring systems with a condensed thiophene ring were also compared.See [1] for our preceding communications.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 474–476, April, 1979.     

Synthesis of 2-R-fluorantheno[2,3-d]- and 2-R-fluorantheno[3,2-d]oxazoles

2-R-Fluorantheno[2,3-d]- and 2-R-fluorantheno[3,2-d]oxazoles were synthesized, and their UV and IR spectra were studied. Ten new compounds are described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 905–907, July, 1974.     

Pyrrolopyridazines. 1. Synthesis and reactivity of pyrrolo[2,3-d]pyridazine 5-oxides

Reaction of ethyl 4-ethoxymethyleneamino-3-methoxy-5-pyridazinylpyruvate 1-oxide ( 8 ) under various conditions constitutes a new approach to substituted pyrrolo[2,3-d]pyridazines. The resulting substituted pyrrolo[2,3-d]pyridazine 5-oxides were allowed to react further to provide a number of new compounds in this ring system.     

Synthesis of [5'-13C]ribonucleosides and 2'-deoxy[5'-13C]ribonucleosides

The present efficient synthesis of [5'-13C]ribonucleosides and 2'-deoxy[5'-13C]ribonucleosides is characterized by the synthesis of the D-[5-13C]ribose derivative as an intermediate via the Wittig reaction of 4-aldehydo-D-erythrose dialkyl acetals with Ph3P13CH3I-BuLi to introduce the 13C label at the 5-position of a pentose. This was followed by the highly diastereoselective osmium dihydroxylation for the preparation of 2,3-di-O-benzyl-D-[5-13C]ribose dialkyl acetal and the cyclization from D-[5-13C]ribose dialkyl acetal derivatives to the alkyl D-[5-13C]ribofuranoside derivative by the use of LiBF(4). The obtained D-[5-13C]ribose derivative was converted into [5'-13C]ribonucleosides and subsequently into the corresponding 2'-deoxynucleosides.